The objective of the present invention is to improve on the protective ability or efficiency of the power surge isolator disclosed in the referenced prior application.
It has been found that, occasionally, certain types of excessive power surges can be so fast that they may reach the electrical appliance circuit and damage the same before the protective fuses in the power surge isolator have time to blow.
The present invention deals with this particular problem by augmenting the action of the fuses with a varistor or varistors replaceably connected between positive and negative terminals of the power surge isolator in such a manner that even the occasional abnormal power surges which are so fast that they may bypass the fuses are diverted safely to ground through the varistor or varistors whose resistance or resistances decreased instantly in response to an increase in voltage through the circuit in which they are connected. By employing varistors in conjunction with fuses, according to the present invention, appliances can be protected from damage due to power surges of all conceivable kinds and intensities.
Other objects and advantages of the invention will become apparent during the course of the following detailed description.